This application is based upon, and claims the benefit of priority of, prior Japanese Patent Application 2001-198537 filed on Jun. 29, 2001, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a fuel supply apparatus that draws in and discharges fuel from a jet pump to a sub tank.
2. Description of Related Art
Generally, there is known a fuel supply apparatus having a fuel pump which is housed in a sub tank that is located within a fuel tank, in which, even if a liquid level of fuel contained in the fuel tank is lowered, a level of fuel in the sub tank is maintained at a level so that the fuel can be drawn in by a fuel pump. A fuel supply apparatus of the type mentioned above operates such that when return fuel, i.e. fuel returned from an engine or the like, is fed to a jet pump, and fuel within the fuel tank is thereby drawn upward by a suction pressure produced when the fuel is injected from a jet nozzle of the jet pump, that is lower than atmospheric pressure. Then, a jet stream of the drawn fuel, together with the fuel within the fuel tank, are delivered into the sub tank. By delivering the fuel within the fuel tank into the sub tank through the jet pump, the level of the fuel within the sub tank is kept higher than the level of the fuel within the fuel tank. Consequently, even if the fuel remaining in the fuel tank becomes smaller in volume, the fuel pump is properly able to draw in and discharge the fuel within the sub tank.
Depending on a placement location or other conditions, the fuel tank may need to be made lower in profile (height). Using a low-profile fuel tank necessitates using a low-profile sub tank which is placed within the fuel tank. The shallow sub tank requires a larger bottom surface area to secure a sufficient capacity. The larger the bottom surface area of the sub tank, the larger an area of a suction filter that extends over the inner bottom portion of the sub tank. The suction filter serves to remove foreign substances entrained in the fuel when the fuel pump draws in fuel within the sub tank. If a vehicle corners or travels on steeply inclined ground with a low volume of fuel within the sub tank, a part of the suction filter may not be exposed to the fuel within the sub tank, resulting in the surface of the suction filter from running out of a liquid. This causes the fuel pump to draw in fuel and air through the suction filter. As a result, the suctioning capability and pressure-applying capability of the fuel pump are deteriorated, leading to a decrease in fuel discharge amount.
In view of the foregoing, an object of the present invention is to provide a fuel supply apparatus which is designed so that the level of the fuel within the sub tank is maintained at an appropriate level and so that running out of a liquid film on the filter is prevented even when the fuel within the sub tank is small in quantity. That is, the filter will be submerged in liquid fuel at all times, even when the volume in the tank is low in volume.
In a fuel supply apparatus according to a first aspect of the present invention, a fuel flow changing member serves to change a direction of fuel delivered from a jet pump that flows along an inner bottom surface from an upward direction into a lateral direction. This decreases the momentum of the fuel flow delivered from the jet pump to the sub tank. Since the fuel is prevented from flowing out of the sub tank, the level of the fuel within the sub tank can be maintained at an appropriate level.
Moreover, the fuel flowing upwards from the inner bottom surface changes its direction to flow sideways so as to reach the upper side of the filter. Thus, even if the fuel within the sub tank becomes smaller in volume, the filter is splashed with fuel from above. This prevents the surface of the filter from not being exposed to fuel at all times. Consequently, even if the fuel within the sub tank becomes smaller in volume, the fuel pump is properly able to draw in and discharge fuel.
In the foregoing construction description, the flow of fuel delivered from the jet pump into the sub tank may strike a fuel receiving portion, and may then be let out from an opening portion via an introducing portion. This facilitates conversion of the fuel flow direction. Moreover, by using a tubular member, the fuel flow changing member having the fuel receiving portion, the introducing portion, and the opening portion formed therein can be constructed with ease.
In the foregoing construction, a partition wall may serve to prevent the fuel from flowing into the sub tank and traveling in a direction other than a direction toward the fuel flow changing member. This will permit the fuel to flow solely toward the fuel flow changing member. Consequently, fuel is efficiently splashed on the filter. Further, fuel may be permitted to cross over the partition wall so as to flow easily toward the upper side of the filter. Thus, with a simple structure, the surface of the filter can be splashed with fuel and thereby remain covered with fuel.
In the foregoing constitution, first and second slant faces may be placed apart from each other. This allows the fuel having struck the second slant face after flowing along the first slant face to be widely scattered in the direction of the filter. Consequently, the surface of the filter not exposed to the fuel can be uniformly wetted or covered by the fuel.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.